Fix Button click after Dark to Light color mode switch

src/System.Windows.Forms/PublicAPI.Unshipped.txt

@@ -0,0 +1 @@
+override System.Windows.Forms.ButtonBase.OnSystemColorsChanged(System.EventArgs! e) -> void

src/System.Windows.Forms/System/Windows/Forms/Control.cs

@@ -12608,6 +12608,12 @@ protected virtual void WndProc(ref Message m)
 
                     // Left here for debugging purposes.
                     // string? text = m.LParamInternal == 0 ? null : new((char*)m.LParamInternal);
+                    if (m.LParamInternal != 0
+                        && Application.ColorModeSet
+                        && new string((char*)m.LParamInternal) is "ImmersiveColorSet")
+                    {
+                        OnSystemColorsChanged(EventArgs.Empty);
+                    }
 
                     if (action is SYSTEM_PARAMETERS_INFO_ACTION.SPI_SETNONCLIENTMETRICS && m.LParamInternal == 0)
                     {

src/System.Windows.Forms/System/Windows/Forms/Controls/Buttons/ButtonBase.cs

@@ -1306,6 +1306,12 @@ private protected void UpdateOwnerDraw()
         }
     }
 
+    protected override void OnSystemColorsChanged(EventArgs e)
+    {
+        UpdateOwnerDraw();
+        base.OnSystemColorsChanged(e);
+    }
+
     /// <summary>
     ///  Determines whether to use compatible text rendering engine (GDI+) or not (GDI).
     /// </summary>

src/test/unit/System.Windows.Forms/System/Windows/Forms/ButtonBaseTests.cs

@@ -9246,6 +9246,51 @@ public void ButtonBase_WndProc_InvokeSetStateWithHandle_Success(FlatStyle flatSt
         Assert.Equal(0, createdCallCount);
     }
 
+    [WinFormsFact]
+    public static void ButtonBase_OnSystemColorsChanged_StandardFlatStyle_RestoresOwnerDraw()
+    {
+        using SubButtonBase control = new()
+        {
+            FlatStyle = FlatStyle.Standard
+        };
+
+        control.SetUserPaintAndUserMouseStyles(false);
+
+        Assert.False(control.GetUserPaintStyle());
+        Assert.False(control.GetUserMouseStyle());
+
+        control.OnSystemColorsChangedEntry(EventArgs.Empty);
+
+        Assert.True(control.GetUserPaintStyle());
+        Assert.True(control.GetUserMouseStyle());
+    }
+
+    [WinFormsFact]
+    public static void ButtonBase_OnSystemColorsChanged_SystemFlatStyle_ClassicMode_ClearsOwnerDraw()
+    {
+        RemoteExecutor.Invoke(static () =>
+        {
+#pragma warning disable WFO5001
+            Application.SetColorMode(SystemColorMode.Classic);
+#pragma warning restore WFO5001
+
+            using SubButtonBase control = new()
+            {
+                FlatStyle = FlatStyle.System
+            };
+
+            control.SetUserPaintAndUserMouseStyles(true);
+
+            Assert.True(control.GetUserPaintStyle());
+            Assert.True(control.GetUserMouseStyle());
+
+            control.OnSystemColorsChangedEntry(EventArgs.Empty);
+
+            Assert.False(control.GetUserPaintStyle());
+            Assert.False(control.GetUserMouseStyle());
+        }).Dispose();
+    }
+
     private class SubButton : Button
     {
         public new bool GetStyle(ControlStyles flag) => base.GetStyle(flag);
@@ -9377,6 +9422,17 @@ private class SubButtonBase : ButtonBase
         public new void SetStyle(ControlStyles flag, bool value) => base.SetStyle(flag, value);
 
         public new void WndProc(ref Message m) => base.WndProc(ref m);
+
+        public void OnSystemColorsChangedEntry(EventArgs e) => OnSystemColorsChanged(e);
+
+        public bool GetUserPaintStyle() => GetStyle(ControlStyles.UserPaint);
+
+        public bool GetUserMouseStyle() => GetStyle(ControlStyles.UserMouse);
+
+        public void SetUserPaintAndUserMouseStyles(bool value)
+        {
+            SetStyle(ControlStyles.UserPaint | ControlStyles.UserMouse, value);
+        }
     }
 
     protected override ButtonBase CreateButton() => new Button();

src/test/unit/System.Windows.Forms/System/Windows/Forms/ControlTests.cs

@@ -1201,6 +1201,54 @@ public void Control_Region_AssignNull_ShouldBeNull()
         control.Region.Should().BeNull();
     }
 
+    [WinFormsFact]
+    public static void Control_WndProc_WM_SETTINGCHANGE_ImmersiveColorSet_RaisesSystemColorsChanged()
+    {
+        RemoteExecutor.Invoke(static () =>
+        {
+#pragma warning disable WFO5001
+            Application.SetColorMode(SystemColorMode.System);
+#pragma warning restore WFO5001
+
+            using SubSystemColorsChangedForm form = new();
+
+            int systemColorsChangedCallCount = 0;
+            form.SystemColorsChanged += (_, _) => systemColorsChangedCallCount++;
+
+            Assert.NotEqual(IntPtr.Zero, form.Handle);
+
+            form.SendWmSettingChange("ImmersiveColorSet");
+
+            Assert.Equal(1, systemColorsChangedCallCount);
+            Assert.Equal(1, form.OnSystemColorsChangedCallCount);
+        }).Dispose();
+    }
+
+    private class SubSystemColorsChangedForm : Form
+    {
+        public int OnSystemColorsChangedCallCount { get; private set; }
+
+        public unsafe void SendWmSettingChange(string settingName)
+        {
+            fixed (char* settingNamePtr = settingName)
+            {
+                Message message = Message.Create(
+                    Handle,
+                    (int)PInvokeCore.WM_SETTINGCHANGE,
+                    wparam: IntPtr.Zero,
+                    lparam: (IntPtr)settingNamePtr);
+
+                WndProc(ref message);
+            }
+        }
+
+        protected override void OnSystemColorsChanged(EventArgs e)
+        {
+            OnSystemColorsChangedCallCount++;
+            base.OnSystemColorsChanged(e);
+        }
+    }
+
     private class OnCreateControlCounter : Control
     {
         public int OnCreateControlCount { get; set; }